PLANT PATHOLOGY- EXAM 3

vector

an organism that transmits a pathogen from one host to another

virus

infectious agent made up of nucleic acid surrounded by a protein coat

viruses are not _______ organisms because they _______ ________ _________, they don't have _______ to _______ _______ _______, and they do not have an outer _________.

living, cannot replicate themselves, enzymes, catalyze chemical reactions, membrane

nucleic acid in a virus can be _____ or ______, being ____ or ____ stranded

RNA, DNA, double, single

in order to infect and multiply, viruses must be inserted into...

a living cell

virus particle shapes

bacilliform, icosahedral, rods, flexuous rods

transcription

DNA is replicated to make mRNA

what makes mRNA during transcription

RNA polymerase

translation

mRNA becomes a protein

what does tRNA bring to ribosomes to make proteins during translation

amino acids

proteins are a result of

ribosomes + mRNA + tRNA

inclusion body

aggregation of virus particles that can be detected by a light microscope

inclusion bodies are formed by

plant viruses

inclusion bodies significance

result of virus infection, helpful for detection

why do viruses persist?

they have no immune systems

viral disease management

toss infected plants, vector control, heat treatment

heat treatment

heat slows down virus growth, cut off and replant non-infected part of plant

most common way that viruses spread

insects and mites (vectors), vegetative propagation

viruses are ________, and they do not cause _______

biotrophs, necrosis

necrosis

death of cells or tissue

symptoms of viral disease

mosaic, yellowing, ring spots, cankers, etc

non-persistent transmission

virus stays in mouth part of insect, moves on rapidly

persistent transmission

virus passes through insect and enters salivary glands

epidemic

widespread occurrence of an infectious disease ina. community at a particular time

epidemiology

the study of how diseases increase and spread

6 types of epidemics

local, regional, endemic, pandemic, sporadic, cyclic

local

impacts a small area, like a town

regional

impacts a region, like the northeast

endemic

large area, occurs yearly under certain conditions, low mortality, like the flu

pandemic

huge areas, significant mortality, like covid

sporadic

large area, irregular occurences

cyclic

occurs after a set amount of time, like 17 year cicadas

epidemic pyramid

pathogen, host, environment, time

epidemic vs. pandemic

epidemic is in a specific location, pandemic is worldwide

what is one of the critical predictors of disease epidemic occurence

leaf wetness

abiotic diseases are not

infectious, living, or continuous

abiotic diseases are better considered as

injuries

2 categories of abiotic plant disease causes

caused by excesses or deficiencies, caused by exposure to harmful chemicals

excessives and deficiencies that can cause abiotic diseases

high/low temp, drought/flooding, not enough light/ sun scald, not enough/toxic nutrients

what can low temperatures do to plants

reduce nutrient uptake, growth, yield, and increase susceptibility

what can high temperatures do to plants

wilting, reduce growth and yield, increase susceptibility

drought causes

wilts and poor yield

too much water causes

less oxygen, oomycete growth, poor growth

defoliation is a result of

too much sun

what do plants that recieve too little light develop

chlorosis

chlorosis

yellowing of leaves

which type of nutrient is more likely to be deficient? Micro or macro?

macronutrients

ozone is formed by

photochemical reactions, sunlight, nitrous oxides, oxygen

fluoride is found in

water and phosphate fertilizers

sulfur dioxide comes from

coal, petroleum, volcanoes

chlorine comes from

transportation accidents

these pollutants affect plants from the ______ they are released in

plume

point source air pollutants

come from a clear location, fluoride, sulfur dioxide, chlorine

non point source air pollutants

affect plants over large area, require light to be active

examples of non point source air pollutants

Ozone, PAN

PAN

peroxyacyl nitrates

PAN is also referred to as

smog

dissemination

spread

inoculum

the infectious material that starts disease

primary inoculum

starts the disease

secondary inoculum

spreads the disease further

how do pathogens enter plants

spores, direct penetration, stomata, wounds

stomata

natural openings

which enzymes are used to break into plants

cutinase, cellulase, pectinase

cutinase

breaks down cuticle

pectinase

breaks down middle lamella

cellulase

breaks down cell walls

structural plant tools to stop pathogens

cuticle wax, thick cell walls, lignin

lignin

substance that makes cell walls rigid

chemical plant tools to stop pathogens

phenols, toxins, inhibitors

phenols

defense chemicals

induced plant defenses

callose and PR proteins

cutin

waxy polymer in the cuticle, blocks penetration

immunity

no chemical reaction between pathogen and desired host, so the host is immune

pathogenicity

ability of a pathogen to cause a disease

tolerance

plant is infected but shows little damage

susceptibility

the plant cannot defend itself

resistance

the plant can recognize and defend against the pathogen

elicitor

molecule produced by the pathogen that induced a host response

avirulence gene

the pathogen gene that produces the elicitor

what do avirulence genes do

they tell the host it is being attacked

true or false: virulence and avirulence genes produce the same things, but the plant can only detect the avirulence genes

true

what happens when a plant is aware it is being attacked

it is able to defend itself

what is the product of avirulence genes

MAMPs

MAMP

microbe associated molecular patterns

when a host plant recognizes a _______, it begins a cascade of _____

MAMP, defenses

what three things are the same

elicitor= MAMP= avirulence genes

what are he 2 types of plant defense

induced and constitutive

consititutive plant defense

always present, pre-formed

consititutive plant defense examples

cell wall thickness, cutin, waxes, fungitoxic exudates, inhibitors

induced plant defense

forms in response to disease attack

induced chemical defenses

PR proteins, phyotalexins

phytoalexins

antimicrobials produced by plant as a response

PR proteins

pathogenesis related proteins

induced physical defenses

callose deposition, cell wall thickening

callose

strengthens cell wall at fungal penetration point

callose is

one of the first plant defense reactions

true or false: callose requires induction of transcriptional plant activity

false: it does not

what turns on plant defenses

elicitors

SAR

systemic acquired resistance